Koh Phra Thong is known to be one of the major nesting sites in Thailand for the Olive Ridley turtle, Green turtle and Leatherback turtle.
Naucrates, in collaboration with local groups, Phuket Marine Biological Center (PMBC) and the Department of Marine Coastal Resources, is responsible for monitoring nesting beaches in the Andaman sea.
Although the number of nests has dramatically decreased over the past few years, the long-term monitoring effort continues every year.
In December 2019, we recorded a nest of an Olive Ridley turtle; the first one we had seen for a few years.
Finding turtle nests represents hope for the future and a reward of our long-term monitoring efforts. Marine turtles are known to return to lay eggs on the beach where they were born, after they reach maturity, (15-30 years).
Monitoring the beach on a daily basis, early in the morning, is one of the activities that helps us to collect data on the presence of turtles on Koh Phra Thong and better understand their overall activity in the Andaman Sea area.
Graph 1: Sea turtle nests per season (1996-2019)
The last nest of a leatherback turtle was observed in 2011. This season (2020) we have found the tracks of leatherback on the beach. After nine years it seems that the leatherback has decided to return to the island. This gives us hope!
Data for KPT, collected by PMBC, indicates a reduction of 82% in the number of Olive Ridley nests from 1979 (n = 238) to 1990 (n = 42) (Chantrapornsyl, 1992a). A similar decrease was observed in the data collected from 1996 to 2006, although the methodologies were different. From 2007 to 2010 there was an increase in the of number of nests, (with the exception of 2009, when no nests were found.) This was due to an increase of nesting activity of Green and Leatherback turtles (Graph 1).
In the last five years (2010-2015) the number of nests has varied, showing an increase in the last two years, with dominance of Green turtle nests.
Historical data shows a massive sea turtle egg harvest, estimated at about 400,000 eggs per year in Thailand, of which 60,000 were from the Phang Nga province (Polunin, 1975), where PT island is located. Egg harvesting, the consumption of turtle meat and the hunting of turtles for their shells should be considered as additional contributions to the decrease noted at PT island.
The drastic decline of sea turtle nests along the south west coast of Thailand indicates that only a few nesting females have survived in the area.
Further investigations would be needed to estimate the impact of fisheries on sea turtles. The number of big fishing boats (trawlers, gill nets, squid boats, etc.) that are fishing in the area is high and nothing is known about their impact on natural resources. We can assume that a lot of the trash found on the beaches originates from the fishing boats, as there is a lot of styrofoam, squid traps, fishing floats, glass and plastic bottles etc. Present. It has also been proven that many turtles drown in trawling nets. During the season fishing activities were observed within 100 meters from the shore, using tangle nets. This specific fishing method could have a significant impact during the sea turtle nesting season, creating obstacles for the nesting females and hatchlings. There are also a very large number of fishing vessels situated along the horizon line at night. They appear to be very close together, and fishing with exceptionally bright lights. This may form a barrier to any female turtles that want to approach the island during the night and may have an overall devastating impact on the population of nesting females, as well as the survival of any hatchlings from KPT and KR.
Coastal degradation and future tourism development
Marine turtle nesting beaches are increasingly being degraded by coastal development activities and pollution all over Thailand. Habitat destruction is one of the main threats to marine turtles’ survival. Tourist development on the island is still limited, but it is increasing year by year. New facilities are built near the beach every year and building permits are not always obtained by resort owners. This should be assessed and further development limited unless the appropriate permits have been issued.